Antimicrobial activities and phytochemical properties of Annona muricata leaf

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1 Covenant Journal of Physical & Life Sciences (CJPL) Vol. 5 No. 2, Dec 2017 An Open Access Journal available online Antimicrobial activities and phytochemical properties of Annona muricata leaf Olugbuyiro J. A. O.* 1, Omotosho O. E. 2, Taiwo O. S. 2, Ononiwu F. O. 1, Banwo A. S. 1, Akintokun O. A. 1, Obaseki O. S. 3 & Ogunleye, O. M. 1 1 Department of Chemistry, Natural Products Unit, Covenant University, P.M.B. 1023, Ota, Nigeria. 2 Department of Biological Sciences, Covenant University, Canaan Land P.M.B. 1023, Ota, Nigeria. 3 Department of Industrial Physics, Covenant University, Canaan Land, P.M.B. 1023, Ota, Ogun State, Nigeria. *Corresponding author: Dr. Joseph A.O. Olugbuyiro Department of Chemistry, Natural Products Unit, Covenant University, P.M.B. 1023, Ota, Nigeria. <joseph.olugbuyiro@covenantuniversity.edu.ng> <olugbuyiro@yahoo.com> Abstract: Annona muricata is a well-known economic and traditional plant of Nigeria. The study investigated the properties of constituents and antimicrobial activities of extracts of the leaf of A. muricata. The extracts were tested against Escherichia coli, Pseudomonas aeuroginosa, Staphylococcus aureus and Candida albicans by the agar well diffusion method at concentration of 20 mg/ml. The methanol (AM2) and ethyl acetate (AM4) extracts were characterized using UV and IR spectroscopy. The morphological structure of the A. muricata leaf was observed at a magnification of 20,000X using SEM and then subjected to EDX analysis. The results of the phytochemical screening revealed the presence of phenolic compounds, flavonoids, tannins, alkaloids, saponins and cardiac glycosides in the extracts. Anthraquinone was found absent. The ethyl acetate extract was found highly active against gram positive bacteria, S. aureus (ZI of 42 mm; AI = 1.31) and ampicillin resistant gram negative P. aeruginosa (ZI of 34 mm; AI = 1.13). The IR spectra of AM2 and AM4 extracts of A. muricata showed peaks at a frequency of 3377 cm -1 to 3440 cm -1 indicating the presence of a phenolic OH stretch. This supports the phenolics detected chemically. The UV spectrum of methanol extract showed peaks that are typical of flavonoids and phenolics. The SEM revealed the sizes of the leaf particles as inhomogeneous. EDX results showed high oxygen concentration 40

2 of 73.5 % and carbon concentration of 26.5 %.The findings proved the antiinfective potential of Annona muricata leaf and established physico-chemical markers for the active extracts. Keywords: Annona muricata, phytochemical, antimicrobial, infections Introduction Annona muricata belongs to the family of Annonaceae. It is reputed for its edible fruit that is commonly called soursop [1]. The fruit has slight acidic taste when ripe. Annona muricata is used in traditional medicine in many regions. The fresh leaves when crushed are applied on skin eruption for quick healing. A poultice of young A. muricata leaf is applied on the skin to alleviate rheumatism and other skins like eczema. When applied during the healing of wounds it results in less or no skin scars [2]. The decoction can also be used as wet compress on swollen feet and other inflammations. The juice of the fruits is taken orally as herb remedy of arthritis, haematuria and liver ailments [3]. The leaf tea is used for catarrh in the Peruvian Andes. The seed extracts are used to kill external parasites, head lice, and worms [4, 5]. In the Peruvian Amazon, the bark, root and leaves are used for the treatment of diabetes as well as sedative and antispasmodic drugs. The leaf or bark tea or combination of both is used as a sedative and heart tonic by the indigenes of Guyana. In the Brazilian Amazon, a leaf tea is used for liver problems and the oil of the leaves and unripe fruit is mixed with olive oil and used externally for neuralgia, rheumatism, and arthritic pain [3]. It was reported [6] that A. muricata crude extract samples exhibited different level of cytotoxicity toward breast cancer cell lines. The selected B1 AMCE reduced the tumor s size and weight, showed anti-metastatic features, and induced apoptosis in vitro and in vivo of the 4 T1 cells. Furthermore, it decreased the level of nitric oxide and malondialdehyde in tumor while also increased the level of white blood cell, T-cell, and natural killer cell population. In another work, A. muricata was investigated and reported [7] that a chloroform/methanol (1:1) leaf extract showed a 67 % inhibition of Plasmodium falciparum F32 in vitro at 20 µg/ml. The present study evaluated the antimicrobial potential, phytochemical constituents and the physico-chemical characteristics of the leaf extracts of A. muricata. Materials and Methods The leaf of Annona muricata was collected from Ota, Nigeria. The plant was identified at the herbarium in the Biological Department, Covenant University, Ota. Nigeria. The plant leaf was air-dried for two weeks then crushed and stored in a clean container at room temperature for further analysis. Extraction: The leaf was defatted then extracted with methanol on cold maceration. Extract was strained and filtered over anhydrous sodium sulphate and then evaporated in vacuo at 45 o C. The crude extract was partitioned into chloroform, ethyl acetate and aqueous layers successively using a separating funnel. The concentrated fractions were dried in desiccator and kept for further analysis. Phytochemical screening and analyses: The dried sample of A. muricata (AM) leaf was extracted with 50:50 methanol-water mixture and the leaf extract were tested for tannins, 41

3 phenolics, anthraquinones, flavonoids, alkaloids, saponins and cardiac glycosides according to the modified standard procedures [8]. The UV- Visible spectra were obtained in MeOH on a Genesys 10 UV spectrophotometer while FTIR measurement was run on Perkin-Elmer 2 spectrometer. Scanning electron microscope was run at a magnification of 20 μm to observe clear image of the plant leaf particles in colloid well dispersed with uniform size. The elemental concentration of the plant species was determined by EDX. Antimicrobial test assay: Antimicrobial activity was tested against the following clinical strains of micro-organisms: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans. The modified standard procedures [9, 10] were adopted for the assay. Antibacterial activity assay: Antibacterial activity of the extracts was determined by well diffusion method on nutrient agar medium. Nutrient agar medium is poured in to the petri-plate. After the medium was solidified, the inoculums were spread on the solid plates with sterile swab moistened with the bacterial suspension. A standard cork borer of 9 mm diameter was used to bore a well and equal dose (20 mg/ml) of each of the test samples was transferred into the well with needle syringe. Gentamicin is taken as positive control. The plates were incubated at 37 ºC for 24 hrs. Then antibacterial activity was determined by measuring the diameter of zone of inhibition and Activity Index was calculated. Antifungal activity assay: Antifungal activity of the extracts was determined by well diffusion method on Sabouraud Dextrose agar (SDA) medium. Sabouraud Dextrose agar (SDA) medium is poured in to the petri plate. After the medium was solidified, the inoculums were spread on the solid plates with sterile swab moistened with the fungal suspension. And 0.2 ml of the test sample was introduced into the well at a concentration of 20 mg/ml. The plates were incubated at room temperature of 25 0 C for 48 hrs. Then antifungal activity was determined by measuring the diameter of zone of inhibition and Activity Index was calculated. Results and Discussion Phytochemical Screening The results of the phytochemical screening (Table 1) revealed the presence of phenolic compounds, flavonoids, tannins, alkaloids, saponins and cardiac glycosides as secondary metabolites in the leaf extract of Annona muricata. However, Anthraquinone was found absent in the leaf sample. The previous works [3, 11] agree with the findings of this study. Various reports have indicated tannins, flavonoids and phenolics as free-radical scavengers possessing anti-oxidative properties, antimicrobial properties as well as strong anti-cancer properties [12-14]. 42

4 Table1. Classes of secondary metabolites in Annona muricata leaf Constituent Intensity Phenols +++ Flavonoids ++ Tannins +++ Alkaloids + Cardiac glycosides ++ Saponins + Saponin glycosides + Anthraquinones - Keys: (+++) Intense, (++) Moderate, (+) Mild, (-) Absent. UV-Visible spectral analysis The UV-Vis spectrum of methanol extract showed peaks at 280, 325 and 664 nm which are typical of flavonoids and phenolics. The peak at 325 nm disappeared in the spectrum of ethyl acetate extract which suggests that the metabolite in that region is likely more polar and hydroxylated. Figure 1. UV spectrum of the methanol extract of Annona muricata 3.3. Fourier transform infra-red spectrum: FTIR measurement was carried out for the identification of functional groups (Table 2). The IR 43

5 spectra of the ethyl acetate extract and the methanol extract of A. muricata showed peaks at a frequency of 3377 cm -1 to 3500 cm -1 which indicated a broad hydroxyl group due to hydrogen bonding molecules. The broad OH strongly overlapped the C=C-H str ( cm -1 ) in MeOH extract spectrum (Figure 2) but little hump showed in EtoAC extract spectrum (Figure 3) due to reduction in hydrogen bonding effect. Also the presence of peaks at frequency of 1612 cm cm -1 by the extracts indicated the presence of an aromatic ring C-C=C str. The two functional groups pool together suggest the possibility of the presence of a phenolic compound. The data support the presence of phenolics detected chemically. Phenolic compounds are known to possess good antioxidant property [15]. In the study carried out by Muthu and Durairaj [5], they reported that the hydroalcoholic extract of Annona muricata leaves had total antioxidant capacity (TAC) of IC 50 value of µg/ml. Radical scavenging potentials against superoxide, nitric oxide, hydroxyl, and hydrogen peroxide were found to be effective with IC 50 values , , and µg/ml respectively. The findings suggest Annona muricata leaves to be good source of antioxidants and radical scavenging agent suitable for prevention of human diseases caused by oxidative stress. Table 2. IR spectral values of Annona muricata extracts Sample ν ( in solid state, cm -1 ) AM2 ( MeOH Extract) 3400 (OH str Broad, phenol), C=C-H str (strongly obscured by the broad OH overlapped), 2924, 2854 (C-H str aliphatic),1738 (C=O str ), 1612, 1516, 1447 (C-C=C str) AM4 ( EtOAC fraction) 3400 (OH str Broad, phenol), 2923, 2854 (C-H str aliphatic), 1731( C=O str ), 1608, 1514, 1450 (C-C=C str aromatic ring) 44

6 %T %T cm cm cm cm cm c m cm cm cm cm cm cm cm cm cm cm cm cm-1 Name MAM_1 Description MAM Figure 2. IR spectrum of the methanol extract of Annona muricata (MAM) cm cm cm cm cm cm cm cm cm-1 Name EAM_1 Description EAM cm cm cm-1 Figure 3. IR spectrum of the ethyl acetate extract of Annona muricata (EAM) 45

7 Scanning Electron Microscope The scanning electron microscope (SEM) image at the magnification of 20,000X showing the sample s surface topography is displayed in Figure 4. It reveals the texture as coarse and the leaf particles showed inhomogeneous sizes. Figure 4. Scanning electron microscopy image of Annona muricata Energy Dispersive X-Ray The EDX analysis (Figure 5 and Table 3) gives information on the composition of the elements in the sample. EDX results showed high oxygen concentration of 73.5 % and carbon concentration of 26.5 %. Table 3. EDX result of Annona muricata Element Element Element Number Symbol Name Confidence Concentration Error 6 C Carbon O Oxygen

8 Figure 5. EDX spectrum of elemental concentration of Annona muricata leaf Antimicrobial activities The antimicrobial activities of Annona muricta leaf extracts were displayed in Table 4. The antimicrobial results of the test extracts at a potency of 20 mg/ml were compared with the activity of the standard, Gentamicin (20 µg/ml).the results revealed that the extracts exhibited high to moderate antimicrobial activities with the exception of aqueous extract (AM 5 ). Ethyl acetate extract (AM 4 ) was found highly active against gram positive bacteria, S. aureus (ZI of 42 mm; AI = 1.31) and ampicillin resistant gram negative P. aeruginosa (ZI of 34 mm; AI = 1.13). Also, AM 4 exhibited moderate activities against E. coli (ZI of 22 mm; AI = 0.73) and C. albicans (ZI of 28 mm; AI = 0.89). The hexane extract of Annona muricata (AM 1 ) had the highest zone of inhibition (42 mm) and activity index (1.40) against E. coli followed by the MeOH extract ( ZI = 38 mm; AI = 1.27). The aqueous fraction generally exhibited low activity against the test pathogens, the activity indexes range from 0.73 to 0.63 as compared with reference drug. Solomon-Wisdom et al. (2014) reported that the methanol extract of the plant leaf showed maximum antibacterial activity than aqueous extract. In this work, among the different solvent extracts studied ethyl acetate and hexane showed highest antimicrobial property. The study supports the ethnomedicinal use of Annona muricata for the treatment of infections. 47

9 Table 4. Antimicrobial results of extracts of A. muricata leaf. Organism Zone of inhibition (mm) AM 1 AM 2 AM 3 AM 4 AM 5 Gentamicin Escherichia coli A.I Staphylococcus aureus A.I Pseudomonas aeruginosa A.I Candida albicans A.I Assay 20 mg/ml; AI = activity Index = ZI of test sample/ ZI of standard.; ZI = zone of inhibition Conclusion In this study, Annona muricata leaf has been found rich in phenolic compounds, flavonoids, tannins, alkaloids, saponins and cardiac glycosides as secondary metabolites. However, Anthraquinone was found absent in the leaf sample. The antimicrobial work demonstrated that among the different solvent extracts studied ethyl acetate and hexane showed highest antimicrobial property. The results suggest that purification of methanol extract which was the crude extract enhances the potency of its fractions. Therefore, from the activity References 1. PIER (2008). "Annona muricata L., Annonaceae". Institute of Pacific Islands Forestry: Pacific Island Ecosystems at Risk (PIER). Retrieved July 20, 2017 from nnona_muricata.htm. 2. Hann, J. H. (1996). A History of the Tumucua Indians and Mission. University Press of Florida. pp Solomon-Wisdom, G. O., Ugoh, S. C., Mohammed, B. (2014). Phytochemical screening and antimicrobial activities of Annona indexes, it proves that the ethyl acetate and hexane fractions of A. muricata possess good anti-infective property. The findings revealed the anti-infective potential of Annona muricata leaf and established physico-chemical markers (UV-Vis, IR, SEM, EDX Analyses) for the active extracts which could be valuable in the bioassay guided fractionation and standardization of the vegetable drug. The good antimicrobial property demonstrated by Annona muricata leaf would provide valuable use to the health management if further processed. muricata (L) leaf extract. American Journal of Biological, Chemical and Pharmaceutical Sciences, 2(1): Taylor, L. (2005). Technical Data Report for Graviola (Annona muricata), Sage Press, Austin, TX. Pp Muthu, S., Durairaj, B. (2015). Evaluation of antioxidant and free radical scavenging activity of Annona muricata. European Journal of Experimental Biology, 5(3):

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